Botany; Geotropism; Plants -- Irritability and movements
Oxalis Valdiviana.—Some cotyledons which had lately opened and were
horizontal on March 6th at noon, stood at night vertically up; on the
13th the first true leaf was formed, and was embraced at night by the
cotyledons; on April 9th, after an interval of 35 days, six leaves were
developed, and yet the cotyledons rose almost vertically at night. The
cotyledons of another seedling, which when first observed had already
produced a leaf, stood vertically at night and continued to do so for
11 additional days. After 16 days from the first observation two leaves
were developed, and the cotyledons were still greatly raised at night.
After 21 days the cotyledons during the day were deflected beneath the
horizon, but at night were raised 45°
above it. After 24 days from the first observation (begun after a true
leaf had been developed) the cotyledons ceased to rise at night.
Oxalis (Biophytum) sensitiva.—The cotyledons of several seedlings, 45
days after their first expansion, stood nearly vertical at night, and
closely embraced either one or two true leaves which by this time had
been formed. These seedlings had been kept in a very warm house, and
their development had been rapid.
Oxalis corniculata.—The cotyledons do not stand vertical at night, but
generally rise to an angle of about 45° above the horizon. They
continued thus to act for 23 days after their first expansion, by which
time two leaves had been formed; even after 29 days they still rose
moderately above their horizontal or downwardly deflected diurnal
position.
Mimosa pudica.—The cotyledons were expanded for the first time on Nov.
2nd, and stood vertical at night. On the 15th the first leaf was
formed, and at night the cotyledons were vertical. On the 28th they
behaved in the same manner. On Dec. 15th, that is after 44 days, the
cotyledons were still considerably raised at night; but those of
another seedling, only one day older, were raised very little.
Mimosa albida.—A seedling was observed during only 12 days, by which
time a leaf had been formed, and the cotyledons were then quite
vertical at night.
Trifolium subterraneum.—A seedling, 8 days old, had its cotyledons
horizontal at 10.30 A.M. and vertical at 9.15 P.M. After an interval of
two months, by which time the first and second true leaves had been
developed, the cotyledons still performed the same movement. They had
now increased greatly in size, and had become oval; and their petioles
were actually .8 of an inch in length!
Trifolium strictum.—After 17 days the cotyledons still rose at night,
but were not afterwards observed.
Lotus Jacoboeus.—The cotyledons of some seedlings having well-developed
leaves rose to an angle of about 45° at night; and even after 3 or 4
whorls of leaves had been formed, the cotyledons rose at night
considerably above their diurnal horizontal position.
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